Salmon_Bennett.pdf - Neural correlates of interspecies...

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Neural correlates of interspecies perspective taking in the post-mortem Atlantic Salmon: An argument for multiple comparisons correction Craig M. Bennett 1 , Abigail A. Baird 2 , Michael B. Miller 1 , and George L. Wolford 3 1 Psychology Department, University of California Santa Barbara, Santa Barbara, CA; 2 Department of Psychology, Vassar College, Poughkeepsie, NY; 3 Department of Psychological & Brain Sciences, Dartmouth College, Hanover, NH INTRODUCTION With the extreme dimensionality of functional neuroimaging data comes extreme risk for false positives. Across the 130,000 voxels in a typical fMRI volume the probability of a false positive is almost certain. Correction for multiple comparisons should be completed with these datasets, but is often ignored by investigators. To illustrate the magnitude of the problem we carried out a real experiment that demonstrates the danger of not correcting for chance properly. GLM RESULTS A t -contrast was used to test for regions with significant BOLD signal change during the photo condition compared to rest. The parameters for this comparison were t (131) > 3.15, p(uncorrected) < 0.001, 3 voxel extent threshold. Several active voxels were discovered in a cluster located within the salmon’s brain cavity (Figure 1, see above). The size of this cluster was 81 mm 3 with a cluster-level significance of p = 0.001. Due to the coarse resolution of the

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